This invention relates to a process of preparing 3-(organothio)aldehydes in a reaction of an essentially equimolar mixture of a mercaptan and an unsaturated aliphatic aldehyde by subjecting the reactants to actinic radiation within a specified temperature range and in the absence of an oxygen-containing atmosphere.
The products of the process of this invention are used, for example, as intermediates for the preparation of pesticides and antioxidants and as odorant or flavoring agents.